Computational Fluid Dynamics Modelling of Two-Phase Bubble Columns: A Comprehensive Review
Round 1
Reviewer 1 Report
This review paper presented a detailed review of the CFD modelling of two-phase bubble columns. The models commonly adopted for interfacial momentum exchange, bubble induce turbulence, coalescence, and break-up were described. A quantitative comparison between the different modelling approaches was presented with considering various literature studies and computing the relative errors between the CFD predictions and the experimental data.
Overall, the authors have done a very high level review paper with summarizing all aspects. It is recommend to accept.
Some neglected parts I propose the authors to consider:
1. The CFD and experiment validation accuracy is a challenging issue. What is the status of validation accuracy?
2. Could LES model by more accurate than RANS models?
Some errors when preparing this manuscript:
Line 742, quantitative not quantitatitative
Line 767, multiphase flows is still missing. The authors type ‘i’ not ‘is’.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors presented a review paper on the Computational Fluid Dynamics Modelling of Two-Phase Bubble Columns.
The novelty of the paper is to be clearly stated.
The introduction is relatively short and should be extended.
A bibliometric study (yearly published papers related to the subject) based on Scopus or Web of science data base is to be performed.
The advantages and disadvantages of the Dispersed phase models are to be discussed. The same for the turbulence models.
Interfacial instabilities, are to be discussed with more details.
How can the bubble induced turbulence be studied numerically?
The paper should be checked against misprints and grammatical mistakes.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The study by Besagni et al. presents a comprehensive summary of CFD modeling of two-phase flows in bubble column reactors. The authors present models describing the different forces acting between phases, and then a review of numerical studies highlighting the model parameters, accuracy and limitations are summarized. Comparisons between simulations and experiments are shown for gas hold up volume, void fraction and liquid velocity. Overall, this contribution will be of high interest to engineers and scientists in industry and academia. This review can be accepted after the following questions are addressed. Below are some comments -
COMMENTS
1. I found several overlaps between this review and Ref. 2 (another review article written by Besagni et al.). For instance, Section 2 about the flow regimes is also described in detail in Ref. 2. Furthermore, Fig. 11 and Fig. 12 in this review are identical to Fig. 40 and Fig. 41 in ref. 2. I think this should be fixed and the common sections and figures can be removed to make this contribution shorter by direct reference to Ref. 2.
2. In Line 346, the authors describe a study which looks at gas bubble trajectories in a glycerol-water solution. All the data about prior CFD simulations presented in Table 4, Table 5, Table 6 have used Gas/water as fluids. Are there CFD studies that have investigated hydrodynamics of bubbles in water/glycerol or any other liquid mixtures? Can this easily be implemented in current CFD models?
3. How are the rising bubbles that reach the free surface handled in CFD simulations? Does the model assume that the bubbles which reach free surface disappear or they are made to disappear when they reach terminal velocity in the column?
4. Several minor errors exist in the manuscript. These should be corrected.
Table 4 title : ‘Literatyre’ should corrected to ‘Literature’
Table 7 title, pg 30 and pg 31: ‘Holduop’ should be corrected to ‘Holdup’
Line 766: ‘comphension’ should be corrected to ‘comprehension’
Line 767: ‘i’ should be corrected to ‘is’
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
